Tough bird to ID. Could be an Eastern Phoebe. The Willow Flycatcher has a long broad bill, rather long wingtips, and a weak eye-ring, according to Sibley, so for now that is my guess. A local bird expert widely known as TOE wrote: the bird in your first photo is an Eastern Wood Pewee. The long primary projections, grayish flanks, overall grayish color, and rather unpronounced white wingbars are all very noticeably Pewee. A Willow will be more greenish/ brown in color, will have shorter primary projections, though not as short as a Least, will not have the extensive gray on the flanks and chest, and the wingbars will be more pronounced and buffy. Also, although not always true, Pewees tend to perch out in the open as this one is doing very often, while the Willows and other empids will stay deeper in the brush, but again, this is not always the case. Congrats on a great trip.